Lightning arrester



March 12, E A. ERMOLD' I LIGHTNING ARRESTER Filed Nov. 20, 1925 75 HIM 1 47 K lllll INVENTOR ATTORI QEY- Patented Mar. 12, 1929.

UNITE STATES ELMER A. ERMOLD, 0F PHILADELPHIA, PENNSYLVANIA, ASSIGNOR T0 WIRIT COM- PANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF MAINE.

LIGHTNING ARRESTER.

Application filed November This invention relates to apparatus for use in conjunction with electric circuits to protect apparatus connected in such circuits and to discharge static electr city which mayaccumulate from the atmosphere or result from lightning discharges.

The invention has tor its object to provide a lightning arrester in which the circuit members or electrodes are completely enclosed within and protected by insulating members which are capable of being easily connected or disconnected, the parts thereof being so arranged that the fixed adjustment of the electrodes may be readily changed if found necessary upon final testing of. the instrument.

Another object is to provide a lightning arrester which may be easily and permanently secured to a supporting wall to present a neat appearance.

When an outdoor aerial is employed in operating a radio receiving circuit, a lightning arrester is preferably connected across the aerial to ground between the aerial and the receiving circuit to serve as a means of discharging static electricity which may accumulate from such sources as lightning. A general form of lightning arrester for such a use is shown in the accompanying drawings; its action depends upon the tendency of a disruptive or impulsive discharge of electricity to traverse an alternative path including an air gap. rather than a longer. though better conducting. path and the length of the included air gap determines the minimum voltage from which the instrument will provide protection. It is essential. thercforefthat the fixed air gap in a given arrester have the proper value to afford the protection for which the instrument was designed. Consequentl; provision for adjusting or regulating the fixed air gap in an arrester is preferably included in the construction.

Other general characteristics which are desirable in lightning arresters are compactness, ruggedness. and simplicity of construction. In addition lightning arresters which are adapted tor use in the protection of radio receiving sets are preferably so constructed that they can be easily and permanently secured to the exterior ot a building, for

20, 1925. Serial N0. 70,233.

ample, to present an appearance which is neat orderly and in harmony with other exterior fixtures for buildings.

The present invention provides a lightning arrester which possesses the various essential characteristics outlined above and is Well adapted for use across an outdoor aerial employed with a radio receiving circuit.

Briefly this is accomplished by constructing a lightning arrester composed of tubular members of such forms as to be readily assembled and having conducting members projecting axially inward with their ends approaching contact at a point on one side of the meeting plane of the tubular members. With this construction the air gap may be readily increased or decreased as is required in View of the final testing of the instrument.

Another feature of the invention comprises a flange or shoulder located on the exterior of one of the tubular members and adapted to support a bracket Without danger of arcing between the instrument and the bracket during a storm.

The invention will be more thoroughly understood with the aid of the descritpion to be given in connection with the accompanying drawings in which:

Fig. 1 is a side view of a lightning arrester constructed in accordance with the invention.

Fig. 2 is a bottom view of the arrester shown in Fig. 1.

Referring to the drawings, a lightning arrester constructed in accordance with the in vcntion comprises upper and lower tubular members 3 and 4 preferably composed of an insulating and waterproof material such as a molded phenol condensation product and current conducting members or electrodes 6 and 7 extending axially in opposite directions from the ends of the tubular members and rigidly secured to these members during the molding process, to which end the electrodes are provided with knurled annular ridges. as

shown. Since the lightning arresters are commonly secured to the exterior of buildings and are therefore subject to the action of storms and moistures, the members 3 and 4 are preferably so constructed and joined as to prevent the entrance of foreign materials and particularly moisture or liquid into the enclosure 5. To this end. the members 3 and 4 are closed at one end and seated at their open ends by giving: the upper member an internal thread a n d the lower member a corresponding e *rnal thread. As a further means of insuiunfz the protection enclosure t'rom moisture and particularly during storn the upper closed end of the upper memoer is provided with a petticoat llt) which may be formed thereon during the molding preces;

In accordance with a feature of the invention, the electrodes 6 and T extend axially in opposite directions tre the ends o the menu bers 3 and 4-. the r ends approachiup contact at a point wholly within one t the tubular members. to the embodiment shown herein, the electrealc projects ir n: the lower tutu lar member and extends ittfl-Httl the plane oi" meeting of the members 3 and 4, thereby placing the air gap bet ween the e eitrwlrs beyond said meeting plane and wholly within the upper member 3. ith this arrangement of parts. the fixed spacing; between the ends oi the electrodes may be readil" increa ed by shortening electrode 7 at its free end, or decreased by reducing the length o the upper part 3 at its open end. It will be oh. as. however, that electrode 6 ins he made to extend to a. point within the lower part it' desired, as an alternative form has the embodiment illustrated.

When a lightning arrester is placed in the open or exposed to the elements. as on the ex:- terior ot a building. arcing during; storms between the lead-in te animal 8 and the supporting device may he encountered when the petticoat 10 is wet or these elements become disarranged and said tern'iinal is in close proximity to the supporting lllilt'lttt. In order to obviate this difficulty. provision is made wher by the body of the arrester cannot slip down on its supporting. member or hrzn'ltet li. by 't'orn'iingr a flange or shoulder 12 on the lower member 4-. The flange may conveniently be formed by reducing the diameter of the lower member as shown to tit the eye of the bracket. With this arrangement of the parts the instrument may be securely supported so as to have an air gap of definite fined length between the lower edge of the petticoat l0 and the bracket 1 1. thereby substantially el iminathas" all danger ot' arcing across the outer surface ot the insulating member.

ln using); the l ghtn' in arrestcr to protect a radio recehdng c-rcu t for exan'iple. it is comic-{ted by means of bind ng posts or terurinals 8 and 9 trout the aerial lead to ground betw en the aerial and the set. The instrument thus serves as an alternative path over the length of air gap determines the minir E roltaec which will be passed to ground 1 of ifblflg through the circuit. the hinns ot' the suitable air gap length will be determined by the particular conditions to be reel in rach instance.

ions means of supporting the arres er tray be employed and in the drawings shown the bracket as composed of a in of sheet metal bent to term a circular eye 13 embracing: the lower insulating menu-hr t and trout whi h cztcnd the paral lel arms ll. ll at the tYtlOllllt ies of which are the fii'f'l fllt-it'tljy' projectmg: teet it, 14 by means of which the bracket may be secured to a Wall or oth r support. Adjacent the eye, the arms of the bracket are spread apart a short d ance as shown to permit them to be tensioncd hr a screw .5 for the purpose of conthe hand portion 13 to firmly clamp ,rom the arrangement of? parts described be sem tha the device comprises a n n'uni number of parts of simple coniction, which may be readily assembled or trsting and capable of being quickly adustcd, by grinding away either the end of h electrode or the end of the wall of one of zhe enter e closing members. it it. is desired to increase or decrease the air gap between the electrode.

In accordan P with the provisions of the )atent statutes the principle of the invention ias been described. and illustrated by the portrayal of a structure which in practice has irored to be. a satisfactory embodiment hereof, but it is desired to hare it understood at the structure shown is merely illustrative. and that the invention may be carried out in other ways.

The invention having: been described, what is claimed as new and desired to be secured by Letters Patent is as 'tollows:-

lo a ligh ning," arrester for radio signal receiving acrials th combination with a lower molded tubular insulating n'iel'nher closed at its lower end and having an exteriorly threaded portion at its upper end. and an annular fl: 1230 located below said threads the lower surface of which co-operates with a s1.apportion bracket. of an upper molded tubular insulat ng member closed at the top and harin r interior screw tl'ireads engaging hose ct the lower member, the open end of raid upper member cup;

ging the upper suri .c of said flange to limit its movement on the lower member. eurren' conducting posts disposed axial]; within said men'ibers and of such relatire lengths that their inner ends are adjacent but diclectrieally separated at a point above the plane of the cud of said lown'iember whereby the gap between the adjacent ends of said posts can be increased by shortening the end of the post projecting beyond the tor-fer member or decreased by cutting away the end face of the upper member, said posts being imbedded in the members at their outer ends during the molding process, to provide solidity thereby insuring a permanent setting of the gap between the posts and to prevent the entrance of moisture within the members, said posts also having provision exteriorly of said n'ienibel's for effecting Wiring, connections to an aerial and ground.

This specification signed and witnessed this seventeenth day of November, 1925.

ELMER A. ERMOLD. 

